The present invention relates to apparatus for liquid cooling by conduction of specific computer components mounted within a housing for a computer in order to reduce the operating temperature of such components.
As certain components for computers, such as microprocessors or hard disk drives become more powerful and complex, while maintaining compact size, more effective thermal management becomes necessary in order to maintain desirable operating temperatures. It is well known that according to the Arrhenius equation, there is an exponential increase in failure rates with incremental increases in operating temperatures. For example, assuming a 1.0 eV activation energy, the failure rate doubles for every 10.degree. rise in operating temperature. Therefore, increases in power of computer chips such as the Pentium.RTM. requires more effective heat management techniques to prevent undesirable rises in operating temperatures.
It is known to apply air-cooled fin modules directly to electronic components in order to dissipate heat through conduction by use of finned heat exchangers and convection with such heat exchangers being cooled by air flow. For example, Intel's 486 microprocessor was cooled by a conformal finned heat exchanger, and Intel's Pentium.RTM. chip has been cooled by finned type heat exchangers which have surface area extending beyond the actual contact surface area of the Pentium.RTM., sometimes known as extended surface heat exchangers. The operating power of certain components such as newer versions of Pentium.RTM. chips of Intel has reached levels which require high volumes of forced ambient air to dissipate generated heat; however, forced air to cool finned modules have limitations in that there may be an upper limit to volumetric flow of cooling air due to noise or other factors such as increased power requirements.
Cooling systems other that finned surface area exchangers are currently known in the prior art. For examples Peltier coolers and heat pipes are known. But, the potential height of Peltier coolers as well as the requirement for extra cooling load due to inherent inefficiencies reduce the probability for successful application to high heat load components. And, heat pipes have heat transfer capacity limitations due primarily to losses in realizing connection to hot and cold thermodynamic reservoirs, but also due to limitations of heat transport due to internal design limits.
It is also known to use cooling plates for circulating liquid coolant, which plates are mounted in contact with various power modules such as transistors, diodes and rectifiers. For example, the EG&G Components Division of Wakefield Engineering of Walefield, Mass. manufactures sheet plates which are bent to conform, that is, crimped about cooling tubes and water-cooled solid copper blocks designed to cool pressure mounted rectifiers and SCR's dissipating up to 2 low per device. The Walkefield cooled plates have several disadvantages in that there is significant thermal resistance across the interface between the copper tube and the aluminum plate, and in that crimping of tubes. in such a manner haves been found to lead to variations in cooling of up to 50 per cent.
A number of prior art patents are directed to the use of liquid coolant to cool electronic components, particularly in large main frame type computers. U.S. Pat. No. 5,159,529 utilizes a plastic internal cooling core having mounted to it one or more cooling plates of copper to receive various electronic components. However, the attachment of cooling plates of copper to a plastic core may cause possible leak problems due to material incompatibility. U.S. Pat. No. 5,144,532 discloses the use of two oppositely positioned liquid cooling plates which are in contact with printed circuits positioned on opposite sides of a multi-layer printed circuit board. U.S. Pat. No. 4,748,495 discloses a liquid cooling module for a plurality of integrated circuit chips arrayed in uneven height wherein cooling fluid is routed either through a group of heat sinks or independently through each of a number of heat sinks. And, U.S. Pat. No. 4,758,926 discloses utilizing heat sinks having microchannels to receive cooling fluid for cooling chips.
While the prior art encompasses the general use of cooling fluid or coolant to cool electronic components, there remains a need to develop a high capacity cooling system for mounting within computer housings for desktop and server size computers where the cooling system is in direct contact with the most powerful and highest heat generating electronic components, such as more recent and more powerful versions of the Pentium processor and hard disk drives. It is accordingly an object of this invention to provide a cooling system specifically directed to such components.